Related Experiment Video
Updated: May 28, 2026
10:32
Fabrication of Uniform Nanoscale Cavities via Silicon Direct Wafer Bonding
Published on: January 9, 2014
Wafer-Level Transfer of GaN-on-Si Light-Emitting Devices via SiO2-SiO2 Direct Bonding: Strain Evolution and
Siyi Zhang1, Shuhan Zhang1, Qian Fan1
1Institute of Next Generation Semiconductor Materials, Southeast University, Suzhou 215123, China.
Micromachines
|May 27, 2026
Summary
We developed a wafer-level transfer for green Gallium Nitride-on-Silicon (GaN-on-Si) light-emitting devices. This process enhances optical performance by removing the silicon substrate and reducing stress, improving device efficiency.
Area of Science:
- Optoelectronics and Materials Science
- Semiconductor Device Physics
Background:
- Gallium Nitride-on-Silicon (GaN-on-Si) optoelectronics face limitations due to silicon's light absorption.
- Existing substrate transfer methods present thermal, optical, and mechanical challenges.
Purpose of the Study:
- To develop a robust wafer-level substrate transfer strategy for 8-inch green GaN-on-Si light-emitting device wafers.
- To investigate the effects of substrate removal on stress and optical performance.
- To analyze optothermal dynamics in transferred devices.
Main Methods:
- Utilized a hybrid planarization process with SiO2-SiO2 direct bonding for wafer-level transfer.
- Precisely eliminated macroscopic steps and achieved sub-nanometer surface roughness for bonding.
- Systematically investigated physical evolution during substrate removal and optothermal behavior.
Main Results:
- Achieved high-yield wafer bonding and effective elimination of macroscopic steps.
- Demonstrated stress relaxation in multiple quantum wells (MQWs) by removing silicon and buffer layers, mitigating quantum-confined Stark effect (QCSE).
- Enhanced relative optical performance by 1.9-fold due to silicon substrate removal and integrated back-surface reflector (BSR), despite increased reverse leakage current.
Conclusions:
- Developed a feasible wafer-level substrate transfer process for GaN-on-Si devices.
- Provided systematic insights into stress relaxation and optothermal behaviors post-transfer.
- Highlighted a potential thermal bottleneck at the bonding interface affecting spectral characteristics.
